Digitized version of the Geologic Atlas of the United States, a set of 227 folios published by the U.S. Geological Survey between 1894 and 1945. Each folio includes both topographic and geologic maps for each quad represented in that folio, as well as description of the basic and economic geology of the area. Maintained by the Texas A & M University Libraries.
Devoted to geology and geology-related topics; includes a large collection of political and thematic maps for the United States and over 100 countries.